A fault monitoring device with anti-noise function

Abstract

The present application provides a fault monitoring device with an anti-noise function, which is applied to the online monitoring of operating faults of oil-immersed equipment, and comprises an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; the oil circuit unit is used to obtain a cooling oil sample from the oil-immersed equipment; the degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested; the gas circuit unit is used to input the gas sample to be tested into the measuring unit; the measuring unit comprises a photoacoustic cell, the photoacoustic cell comprises a first microphone, a second microphone and a differential operator, the differential operator is used to subtract an output signal of the first microphone from an output signal of the second microphone to obtain a photoacoustic signal in the photoacoustic cell, the measuring unit determines the concentration of a characteristic gas in the gas sample to be tested according to the photoacoustic signal, and further determines the operating fault of the oil-immersed equipment.

Description

Technical Field

[0001] The present application relates to the field of oil-immersed equipment monitoring, and in particular to a fault monitoring device with anti-noise function. Background Art

[0002] Oil-immersed equipment is a type of equipment that is immersed in protective oil for a long time and works. The more common oil-immersed equipment is oil-immersed power transformers. Oil-immersed power transformers refer to transformers immersed in oil, and oil is used to protect the transformers. However, during the use of oil-immersed transformers, due to heat and discharge and other reasons, the oil-paper insulation material in the oil-filled electrical equipment will age and decompose, producing a variety of low-molecular hydrocarbons and gases such as carbon dioxide and carbon monoxide that dissolve in the oil. Therefore, the fault and abnormal state of the oil-immersed voltage transformer can be detected according to the type and content of gas in the oil. The existing method for detecting gas in oil is mainly gas chromatography. Gas chromatography refers to manual inspection of the transformer, and the extraction of oil samples and centralized analysis in the laboratory using a gas chromatograph. This method has problems such as high labor and time costs, the test elements are sensitive to oil vapor and humidity, poor environmental adaptability, low detection efficiency, and inability to achieve real-time monitoring.

[0003] Therefore, the existing detection equipment for oil-immersed power transformers has technical problems such as high manpower and time costs, poor environmental adaptability, low detection efficiency, and inability to monitor gas concentration in real time, and needs to be improved. Summary of the invention

[0004] The embodiment of the present application provides a fault monitoring device with an anti-noise function, which is used to solve the technical problems of existing oil-immersed power transformer detection equipment, such as high manpower and time costs, poor environmental adaptability, low detection efficiency, and inability to monitor oil and gas status in real time. It can realize real-time and online monitoring of operating faults of oil-immersed equipment.

[0005] The present application provides a fault monitoring device with an anti-noise function, which includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; wherein:

[0006] The oil circuit unit is used to obtain a cooling oil sample from the oil-immersed device and input the cooling oil sample into the degassing unit under the control of a sampling enable signal sent to the oil circuit unit by the control unit;

[0007] The degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested, and input the gas sample to be tested into the gas circuit unit under the control of the degassing enable signal sent thereto by the control unit;

[0008] The gas circuit unit is used to input the gas sample to be measured into the measurement unit under the control of the measurement enable signal sent to it by the control unit;

[0009] The measuring unit comprises a photoacoustic cell, the photoacoustic cell comprises a first microphone, a second microphone, and a differential operator connected to an output end of the first microphone and an output end of the second microphone, the differential operator is used to obtain a photoacoustic signal in the photoacoustic cell by subtracting an output signal of the first microphone from an output signal of the second microphone, and the measuring unit is used to determine the concentration of the characteristic gas in the gas sample to be measured by the photoacoustic signal generated when the narrow bandwidth laser corresponding to the characteristic gas irradiates the gas sample to be measured;

[0010] The control unit is also used to determine the operation failure of the oil-immersed device according to the characteristic gas concentration in the gas sample to be tested.

[0011] The beneficial effects of the present application are as follows: the fault monitoring device with anti-noise function provided by the present application includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit connected to the oil-immersed equipment. Through the joint action of each unit module, real-time and online monitoring of the characteristic gas generated in the oil-immersed equipment is realized, so as to timely and accurately determine the operating fault type of the oil-immersed equipment; in addition, by arranging a first microphone, a second microphone and a differential operator in the photoacoustic pool of the measuring unit, the first microphone measures the photoacoustic signal and environmental noise in the photoacoustic pool, and the second microphone only measures the environmental noise in the photoacoustic pool. The measurement result of the first microphone and the measurement result of the second microphone are subtracted by the differential operator to obtain the photoacoustic signal in the photoacoustic pool, thereby eliminating the influence of environmental noise on the photoacoustic signal detection result, improving the accuracy and sensitivity of the measuring unit in detecting the characteristic gas concentration in the gas sample to be measured, and being conducive to further improving the accuracy and timeliness of the fault monitoring device with anti-noise function in determining the operating fault type of the oil-immersed equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 A schematic diagram of a fault monitoring system according to an embodiment of the present invention;

[0014] Figure 2 is a structural principle diagram of a fault monitoring device with anti-noise function provided in an embodiment of the present application;

[0015] Figure 3is a structural schematic diagram of a fault monitoring device with anti-noise function provided in an embodiment of the present application;

[0016] Figure 4 is a structural principle diagram of a measurement unit provided in an embodiment of the present application;

[0017] Figure 5 A schematic diagram of a first structure of a measurement unit provided in an embodiment of the present application;

[0018] Figure 6 A second structural schematic diagram of a measurement unit provided in an embodiment of the present application;

[0019] Figure 7 is a schematic diagram of the structure of the photoacoustic cell provided in an embodiment of the present application;

[0020] Figure 8 is a circuit schematic diagram of a first sound-to-electric conversion module and a second sound-to-electric conversion module provided in an embodiment of the present application;

[0021] Fig. 9 is a circuit schematic diagram of a subtraction operator provided in an embodiment of the present application;

[0022] Fig.10 is a structural principle diagram of a signal processor provided in an embodiment of the present application;

[0023] Fig.11 A circuit schematic diagram of a first signal amplifying circuit in a signal processor provided in an embodiment of the present application;

[0024] Fig.12 A circuit schematic diagram of a bandpass filter circuit in a signal processor provided in an embodiment of the present application;

[0025] Fig.13 A circuit schematic diagram of a second signal amplifying circuit in a signal processor provided in an embodiment of the present application;

[0026] Fig.14 A circuit schematic diagram of an A / D conversion circuit in a signal processor provided in an embodiment of the present application;

[0027] Fig.15 is a structural schematic diagram of a laser temperature control module provided in an embodiment of the present application;

[0028] Fig.16 It is a schematic diagram of the temperature control circuit in the temperature control module provided in the embodiment of the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0030] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of a fault monitoring system according to an embodiment of the present invention. Figure 2 It is a structural principle diagram of a fault monitoring device with anti-noise function provided in an embodiment of the present application. The fault monitoring system may include an oil-immersed device 11 and a fault monitoring device 12 with anti-noise function, and the fault monitoring device 12 with anti-noise function is connected to the oil-immersed device 11 through a pipeline. Among them, the oil-immersed device 11 includes an oil-immersed transformer, etc., and the oil-immersed transformer includes a transformer and oil for cooling the transformer, and the oil-immersed transformer is used to change the transmission voltage in the line; the fault monitoring device 12 with anti-noise function includes an oil circuit unit 121, a degassing unit 122, a gas circuit unit 123, a measuring unit 124 and a control unit 125, etc., which are used to monitor the operating status of the oil-immersed device 11 to determine the operating fault of the oil-immersed device 11.

[0031] It should be noted that Figure 1 The system scenario diagram shown is only an example. The server and scenario described in the embodiment of the present application are intended to more clearly illustrate the technical solution of the embodiment of the present application, and do not constitute a limitation on the technical solution provided by the embodiment of the present application. It is known to those skilled in the art that with the evolution of the system and the emergence of new business scenarios, the technical solution provided by the embodiment of the present application is also applicable to similar technical problems. The following are detailed descriptions. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments.

[0032] The fault monitoring device 12 with anti-noise function can realize real-time monitoring of the gas in the cooling oil of the oil-immersed equipment 11 to determine the type of fault that already exists in the oil-immersed equipment 11, or the type of fault that is about to occur; for the type of fault determined to be about to occur, the fault monitoring device 12 with anti-noise function can also estimate the time when the fault type will occur.

[0033] In the fault monitoring device 12 with anti-noise function, the oil circuit unit 121 is used to obtain a cooling oil sample from the oil-immersed device 11 under the control of the sampling enable signal sent to it by the control unit 125, and input the cooling oil sample into the degassing unit 122. Optionally, an oil valve and an oil pump are provided in the pipeline connecting the oil circuit unit 121 and the oil-immersed device 11. When the control unit 125 sends the sampling enable signal to the oil circuit unit 121, the oil valve between the oil circuit unit 125 and the oil-immersed device 11 is opened, and the oil pump extracts the cooling oil sample from the oil-immersed device 11 into the oil circuit unit 121, wherein the volume of the extracted cooling oil sample is set according to demand, for example, 60 ml of cooling oil sample is extracted from the oil-immersed device 11. The oil circuit unit 121 inputs the extracted cooling oil sample into the degassing unit 122 for the next stage of degassing operation.

[0034] The degassing unit 122 is used to degas the cooling oil sample to obtain the gas sample to be tested, and input the gas sample to be tested into the gas circuit unit 123, under the control of the degassing enable signal sent to it by the control unit 125. Optionally, the degassing unit 122 can degas the cooling oil sample by headspace degassing, or by using a degassing membrane tube. The headspace degassing method refers to allowing the cooling oil sample to enter the oil tank, discharging the gas above the oil tank, avoiding the original gas in the oil tank from affecting the gas sample to be tested, forming a negative pressure in the oil tank, and then heating the bottom of the oil tank and stirring the cooling oil at the same time to separate the gas sample to be tested in the cooling oil. The degassing method using a degassing membrane tube refers to first extracting the gas in the degassing membrane tube to prevent the original gas in the degassing membrane tube from affecting the gas sample to be tested in the cooling oil sample, and forming a negative pressure in the degassing membrane tube, and then allowing the cooling oil sample to enter the degassing membrane tube, and the degassing membrane tube is provided with a polytetrafluoroethylene nano-separation membrane, and the polytetrafluoroethylene nano-separation membrane is used to separate the gas sample to be tested in the cooling oil sample. The degassing unit 122 is also used to input the obtained gas sample to be tested into the gas circuit unit 123 for the next step of operation.

[0035] The gas circuit unit 123 is used to input the gas sample to be detected into the measuring unit 124 under the control of the measurement enable signal sent to it by the control unit 125. Optionally, the gas circuit unit 123 includes a gas valve and an air pump. When the control unit 125 sends the measurement enable signal to the gas circuit unit 123, the gas valve in the gas circuit unit 123 is opened, and the air pump is started to input the gas sample to be detected in the gas circuit unit 123 into the measuring unit 124, so as to perform the next stage of gas composition and content detection operation.

[0036] The measuring unit 124 is used to detect the composition and content of the gas sample to be detected under the control of the measurement enable signal sent to it by the control unit 125. Optionally, the measuring unit 124 includes a photoacoustic spectrometer, which uses a narrow bandwidth laser corresponding to the characteristic gas to respectively measure the concentration of each characteristic gas in the gas sample to be detected, and the characteristic gas includes hydrogen, carbon monoxide, methane, acetylene, ethylene, carbon dioxide, and ethane. The working principle of the photoacoustic spectrometer is: the gas sample to be detected is irradiated with a laser having a specific frequency, and the gas corresponding to the laser of the specific frequency in the gas sample to be detected absorbs the laser energy and is in an excited state, and then returns to the ground state by releasing heat energy. In the process of releasing heat energy, the surrounding medium is periodically heated at a specific frequency, thereby generating a periodic pressure wave, and then the pressure wave is collected by a device such as a microphonic pickup to form a data curve. The area enclosed by the data curve represents the content of the gas corresponding to the laser of the specific frequency in the gas sample to be detected, thereby realizing qualitative and quantitative analysis of the gas sample to be detected. It should be noted that the so-called narrow-bandwidth laser refers to a laser beam with a small laser frequency fluctuation range and good laser frequency consistency; in the embodiment of the present application, a narrow-bandwidth laser is used to detect the concentration of the characteristic gas. Compared with a laser with ordinary bandwidth, the sensitivity and accuracy of characteristic gas detection are improved, which is conducive to timely and accurate detection of characteristic gases, and determination or early prediction of operating failures of oil-immersed equipment.

[0037] In one embodiment, the characteristic gas refers to the gas separated from the cooling oil that causes the oil-immersed equipment to malfunction; different types of characteristic gases and different concentrations of different types of characteristic gases cause different types of operating failures of the oil-immersed equipment, and when the concentrations of different types of characteristic gases are low, the operating failure of the oil-immersed equipment will not occur, but the operating failure of the oil-immersed equipment can be predicted by predicting the characteristic gases of various types. The characteristic gases that cause the oil-immersed equipment to malfunction include hydrogen, carbon monoxide, methane, acetylene, ethylene, carbon dioxide, and ethane. When measuring the concentration of the characteristic gas in the gas sample to be tested, there may be only one characteristic gas, that is, only one characteristic gas has a concentration greater than 0, while the concentrations of the other characteristic gases are 0.

[0038] See also Figure 3 , Figure 3 : is a schematic diagram of the structure of a fault monitoring device with an anti-noise function provided in an embodiment of the present application. The process of obtaining a gas sample to be tested from an oil-immersed device and transmitting it to the measuring unit by the fault monitoring device with an anti-noise function includes the following stages:

[0039] The first stage is mainly to pump the pressure in the oil tank 210 to the first target pressure, so that a negative pressure is formed between the oil-immersed device 11 and the oil tank 210, so that the cooling oil sample in the oil-immersed device 11 enters the oil tank 210. First, the control unit controls the first drive motor 223 in the air extraction device 220 in the degassing unit to drive the piston 222 to suck the gas in the oil tank 210 into the cylinder 221 in the air extraction device 220, and discharges the gas in the cylinder 221 through the air circuit unit, so that a negative pressure is formed in the oil tank 210. The air circuit unit includes a first air valve 310, a second air valve 320, a third air valve 330 and a fourth air valve 340. For example, the first port 311 and the second port 312 in the first gas valve 310 are connected, and the gas extraction device 220 extracts part of the gas in the oil tank 210 into the cylinder 221, and then the first port 311 and the third port 313 in the first gas valve 310 are connected, and the gas in the cylinder 221 is discharged through the third gas valve 330. Repeat the above steps to reduce the pressure in the oil tank 210 to the first target pressure. For example, the external atmospheric pressure is the standard atmospheric pressure of 100Kpa, and the first target pressure in the oil tank 210 can be 2Kpa. The pressure in the oil tank 210 can be directly obtained by the pressure sensor 230.

[0040] In the second stage, the pressure difference between the oil tank 210 and the oil-immersed device 11 causes the cooling oil sample in the oil-immersed device 11 to enter the oil tank 210. First, the control unit controls the first valve S1 to open so that the oil-immersed device 11 and the oil tank 210 are connected. Due to the pressure difference between the oil-immersed device 11 and the oil tank 210, the cooling oil sample in the oil-immersed device 11 enters the oil tank 210; when the cooling oil sample in the oil tank 210 reaches the height measured by the upper liquid level sensor 211, the control unit controls the first valve S1 to close. The height of the upper liquid level sensor 211 can be set according to the height of the oil tank 210, for example, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210, or the height of the upper liquid level sensor 211 can be set according to the stirring speed of the stirring member 213 in the oil tank 210, for example, when the stirring speed of the stirring member 213 is 2400rpm, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210, when the stirring speed of the stirring member 213 is 3000rpm, the height of the upper liquid level sensor 211 can be 70% of the height of the oil tank 210, To avoid the liquid level height of the cooling oil sample exceeding the critical height of the oil tank 210 when being stirred due to the excessive rotation speed of the stirring member 213, the stirring mechanism 213 is driven to rotate by a rotating magnet 214 connected to a driving motor 215; or, the height of the upper liquid level sensor 211 can be set according to the stirring temperature of the cooling oil sample in the oil tank 210. For example, when the stirring temperature of the cooling oil sample is 50°C, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210; when the stirring temperature of the cooling oil sample is 70°C, the height of the upper liquid level sensor 211 can be 70% of the height of the oil tank 210.

[0041] In the third stage, the gas to be tested in the cooling oil sample enters the measuring unit through the air extraction device 220 and the gas path unit. First, the control unit controls the first port 311 and the second port 312 of the first gas valve 310 to be connected, so that the air extraction device 220 is connected to the oil tank 210, and then the control unit controls the stirring member 213 to stir the cooling oil sample in the oil tank 210, and then the air extraction device 220 extracts the gas to be tested in the cooling oil sample into the cylinder 221 in the air extraction device 220, and then the control unit controls the first port 311 and the second port 312 of the first gas valve 310 to be disconnected, and controls the first port 311 and the third port 313 of the first gas valve 310 to be connected, opens the second gas valve 320 and the fourth gas valve 340, and closes the third gas valve 330, so that the gas to be tested enters the measuring unit through the gas path unit; secondly, repeat the above steps until the pressure in the oil tank 210 reaches the second target pressure, the above air extraction step stops, and the first gas valve 310 is in a closed state. The second target pressure may be equal to or different from the first target pressure, and the specific value of the second target pressure may be limited according to actual conditions.

[0042] In the fourth stage, the cooling oil sample in the oil tank 210 flows back into the oil-immersed device 11. First, the control unit controls the second valve S2 to connect the oil-immersed device 11 with the oil tank 210, and then controls the oil pump S3 to pump the cooling oil sample in the oil tank 210 into the oil-immersed device 11. When the liquid level of the cooling oil sample in the oil tank 210 reaches the height measured by the lower liquid level sensor 212 in the oil tank 210, the control unit controls the oil pump S3 to stop working and close the second valve S2. The height measured by the lower liquid level sensor 212 can be the bottom of the oil tank 210, and the specific position is not limited in detail in this application.

[0043] According to the working process of the above-mentioned fault monitoring device with anti-noise function, since the gas to be tested in the oil tank 210 needs to be degassed within the target degassing time, the stirring speed of the stirring member 213 directly affects the degassing rate of the gas to be tested. For sample oils of different viscosities or temperatures, and at different stirring speeds, the degassing rate of the gas to be tested in the sample oil from the oil-gas separation device in the operating status monitoring device of the oil-immersed device 11 is different. However, the existing operating status monitoring device of the oil-immersed device 11 is usually unable to accurately set the stirring speed of the stirring member 213 in the oil-gas separation device, resulting in a technical problem that the gas to be tested in the sample oil cannot be separated from the oil-gas separation device within the target time. This embodiment mainly determines the first stirring speed of the stirring member 213 by the predicted concentration of the gas to be tested in the cooling oil sample.

[0044] In one embodiment, due to the influence of various uncertain factors, the concentration value of the gas to be measured actually obtained by the measuring unit is generally greater than the initial predicted concentration of this embodiment. Since the cooling oil samples belong to the same batch of cooling oil samples, the stirring speed of the stirring member 213 of the next cycle can be adjusted according to the difference between the characteristic gas concentration value of the current cycle and the predicted concentration. This step may include: obtaining a first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample; judging whether the first difference is greater than a first threshold; if the first difference is greater than the first threshold, according to the correlation between the concentration, degassing time and stirring speed, based on the first difference and the target degassing time, determining the second stirring speed of the stirring member 213 of the next measurement cycle; if the first difference is less than the first threshold, the first stirring speed of the stirring member 213 is the target stirring speed of the stirring member 213 in the current measurement cycle.

[0045] In one embodiment, when a first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is greater than a first threshold value, the stirring speed needs to be adjusted, and the stirring speed of the stirring member 213 has an upper limit, namely, a critical stirring speed. If the difference between the concentration of the characteristic gas in the previous measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is large, the stirring speed of the stirring member 213 needs to be increased to a second stirring speed exceeding the critical stirring speed, and then other adjustment factors need to be adjusted to compensate for the limitation of the stirring speed.

[0046] Specifically, this embodiment uses the correlation between temperature and stirring speed to adjust the stirring temperature of the stirring member 213, that is, the temperature of the cooling oil sample, to compensate for the limitation of the stirring speed when the stirring speed cannot be increased. This step may include: determining whether the second stirring speed is greater than the critical stirring speed of the stirring member 213; if the second stirring speed is greater than the critical stirring speed of the stirring member 213, the critical stirring speed is the target stirring speed of the stirring member 213 for the next measurement cycle; according to the correlation between temperature, concentration and stirring speed, based on the critical stirring speed and the concentration of the characteristic gas, the initial temperature of the cooling oil sample in the next measurement cycle is determined; if the second stirring speed is less than the critical stirring speed of the stirring member 213, the second stirring speed is the target stirring speed of the stirring member 213 for the next measurement cycle.

[0047] In one embodiment, when a first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is greater than a first threshold, the stirring speed needs to be adjusted; and after the stirring speed of the stirring member 213 is increased, the liquid level of the cooling oil sample in the corresponding oil tank 210 will increase. Since the oil tank 210 is connected to the corresponding oil and gas pipeline, the increase in the liquid level of the cooling oil sample may cause the cooling oil sample to enter other devices through the oil and gas pipeline. Therefore, the cooling oil sample in the oil tank 210 has a critical liquid level to prevent the cooling oil sample from entering other components. Therefore, this step may include: obtaining the cooling oil sample in the current measurement cycle The liquid level of the cooling oil sample; judging whether the liquid level of the cooling oil sample is greater than the critical liquid level of the cooling oil sample; if the liquid level of the cooling oil sample is greater than the critical liquid level of the cooling oil sample, the critical liquid level is the liquid level of the cooling oil sample in the next measurement cycle, and according to the correlation between the liquid level, concentration and stirring speed, based on the critical liquid level and the concentration of the characteristic gas, determining the stirring speed of the stirring member 213 in the next measurement cycle; if the liquid level of the cooling oil sample is less than the critical liquid level of the cooling oil sample, the second stirring speed is the target stirring speed of the stirring member 213 in the next measurement cycle.

[0048] In one embodiment, the degassing time of the current measurement cycle is also an important reference value for setting the stirring speed. The degassing time represents the degassing rate of the gas to be measured in the cooling oil sample. If the degassing time is short, the degassing rate of the gas to be measured is large, corresponding to a larger stirring speed, and the stirring speed of the next measurement cycle needs to be reduced to make the degassing time of the gas to be measured equal to the target degassing time; if the degassing time is long, the degassing rate of the gas to be measured is small, corresponding to a smaller stirring speed, and the stirring speed of the next measurement cycle needs to be increased to make the degassing time of the gas to be measured equal to the target degassing time. Therefore, this step may include: obtaining the degassing time of the gas to be measured in the cooling oil sample in the current measurement cycle; judging whether the degassing time in the current measurement cycle is equal to the target degassing time; if the degassing time in the current measurement cycle is not equal to the target degassing time, according to the correlation between the concentration, degassing time and stirring speed, based on the concentration of the characteristic gas in the current measurement cycle and the target degassing time, determine the stirring speed of the stirring member 213 in the next measurement cycle.

[0049] In one embodiment, the suction pressure and suction speed of the suction device 220 in the oil tank 210 can also be used as variables for adjusting the degassing speed, which will not be described in detail in this application.

[0050] In this step, the concentration of the characteristic gas in the gas sample to be measured obtained by the measuring unit is compared with the predicted concentration of the gas to be measured, and the stirring speed or / temperature of the next measuring cycle is adjusted according to the difference between the two, so that the gas to be measured in the cooling oil sample in the next measuring cycle is separated from the degassing unit within the target degassing time.

[0051] For further information, see Figure 4 , Figure 4 1 is a schematic diagram of the structure of the measuring unit provided in the embodiment of the present application. The measuring unit 124 includes a laser 101, a photoacoustic cell 102 and a signal processor 103. Among them, the laser 101 is used to generate a narrow-bandwidth laser of a specific frequency; the photoacoustic cell 102 is the flow channel of the gas sample to be measured in the measuring unit 124, and is also the place where the narrow-bandwidth laser emitted by the laser 101 and the gas to be measured have energy transfer effects, and a microphone is arranged inside the photoacoustic cell 102, which is used to collect the photoacoustic signal generated after the narrow-bandwidth laser is irradiated to the characteristic gas, and convert the photoacoustic signal into an electrical signal and transmit it to the signal processor 103; the signal processor 103 is used to amplify, denoise and other processing operations on the electrical signal transmitted by the photoacoustic cell 101, and generate a data curve, and output the concentration of the characteristic gas in the gas sample to be measured.

[0052] like Figure 5 , Figure 5 This is a schematic diagram of a first structure of a measuring unit 124 provided in an embodiment of the present application, wherein the measuring unit 124 includes a plurality of detection units 21 that do not interfere with each other.

[0053] Specifically, the gas circuit unit 123 is used to control the gas sample to be measured to flow from the gas circuit unit 123 into all the detection units 21 according to the measurement enable signal.

[0054] The detection unit 21 is used to measure the concentration of the characteristic gas using the narrow bandwidth laser corresponding to the characteristic gas to be detected by the detection unit 21 according to the measurement enable signal.

[0055] It should be noted that the characteristic gas to be measured by the detection unit 21 refers to the characteristic gas that the detection unit 21 needs to measure; the detection unit 21 controls the photoacoustic spectrometer in the detection unit 21 according to the measurement enable signal to use a narrow bandwidth laser corresponding to the characteristic gas to be measured by the detection unit 21.

[0056] It should be noted that each of the detection units 21 can independently realize the measurement of a characteristic gas. The gas sample to be measured is flushed into multiple detection units 21. The characteristic gas in the gas sample to be measured can be measured simultaneously by using multiple detection units 21 that do not interfere with each other. Different types of characteristic gases correspond to narrow-bandwidth lasers of different wavelengths. Different detection units 21 can use narrow-bandwidth lasers of different wavelengths to measure different types of characteristic gases in the gas sample to be measured, thereby being able to simultaneously measure the concentrations of multiple characteristic gases in the gas sample to be measured.

[0057] In one embodiment, a plurality of the detection units 21 are connected in series, which can also be understood as a plurality of the detection units 21 being connected in cascade; the gas circuit unit 123 is used to control the gas sample to be tested to flow from the gas circuit unit 123 into all the detection units 21 in sequence according to the measurement enable signal.

[0058] The two adjacent detection units 21 are connected via a connecting pipe L, and a valve is provided on the connecting pipe L, so that the gas samples to be tested can flow into the detection units 21 in sequence, and at the same time, it can be ensured that all detection units 21 do not interfere with each other.

[0059] It should be noted that each of the detection units 21 is provided with an air inlet Lb and an air outlet Lc. When the measuring unit 124 includes m detection units 21, the m detection units 21 are connected in cascade, and the air inlet Lb of the detection unit 21 located at the first stage can also be connected to the gas circuit unit 123 through a connecting pipe L provided with a valve, so as to be connected to the gas sample to be tested flowing out of the gas circuit unit 123; after the gas sample to be tested flows into the detection unit 21 of the first stage, the gas sample to be tested flows into all the detection units 21 in turn through the connecting pipe L; the air outlet Lc of the detection unit 21 located at the last stage can also be connected to the gas circuit unit 123 through a connecting pipe L provided with a valve, so as to flow the gas sample to be tested after the measurement from the detection unit 21 into the gas circuit unit 123, and the gas sample to be tested after the measurement is processed by the gas circuit unit 123 is discharged, so as to avoid the gas to be tested from polluting the environment.

[0060] The air inlet Lb and the air outlet Lc may be located at the same side of the detection unit 21 , so that two adjacent detection units 21 are connected via the connecting pipe L.

[0061] like Figure 6 , Figure 6 This is a schematic diagram of a second structure of the measurement unit 124 provided in an embodiment of the present application.

[0062] In one embodiment, the measuring unit 124 further includes a box K, and all the detection units 21 are disposed in the box K.

[0063] In one embodiment, the box body K may be a cubic structure, and a plurality of slide rails K1 for supporting the detection unit 21 are arranged on the inner wall of the box body K. The plurality of slide rails K1 are arranged at intervals along the height direction of the box body K, and the detection unit 21 corresponds to the slide rails K1 one by one; the detection unit 21 is slidably connected to the slide rails K1 along the length direction of the slide rails K1 to facilitate the inspection and replacement of the detection unit 21. When a detection unit 21 fails, the staff can pull the detection unit 21 out of the box body K for inspection. When the detection unit 21 cannot be repaired, the faulty detection unit 21 can be replaced with a normally functioning detection unit 21 to avoid the measurement unit 124 from failing to work when a single detection unit 21 fails.

[0064] In one embodiment, the box body K is further provided with an interface K2, at least one of which is connected to the control unit 125, and the detection unit 21 is provided with a connector K3 matching the interface K2, and the connector K3 is plugged into the interface K2. An information interaction bridge is built by connecting the interface K2 and the connector K3 to realize information interaction between the control unit 125 and the detection unit 21, thereby realizing the control of the detection unit 21 by the control unit 125 and the information feedback of the detection unit 21 to the control unit 125.

[0065] See also Figure 7 , Figure 7 1 is a schematic diagram of the structure of the photoacoustic cell 102 provided in an embodiment of the present application. In one embodiment, the measuring unit 124 includes a photoacoustic cell 102, the photoacoustic cell 102 includes a first microphone 1021, a second microphone 1022, and a differential operator 1023 connected to the output end of the first microphone 1021 and the output end of the second microphone 1022, the first microphone 1021 and the second microphone 1022 are respectively used to obtain the sound signal in the photoacoustic cell 102, the differential operator 1023 is used to obtain the photoacoustic signal in the photoacoustic cell 102 by subtracting the output signal of the first microphone 1021 from the output signal of the second microphone 1022, and the measuring unit 124 determines the concentration of the characteristic gas in the gas sample to be measured by the photoacoustic signal generated when the narrow bandwidth laser corresponding to the characteristic gas irradiates the gas sample to be measured.

[0066] It should be noted that after the narrow-bandwidth laser is irradiated to the characteristic gas in the photoacoustic cell 102, a photoacoustic signal will be generated. By testing and analyzing the photoacoustic signal, the concentration of the characteristic gas in the gas sample to be tested can be obtained; when using a microphone to test the photoacoustic signal, a part of the noise in the environment will also be captured by the microphone, which will affect the accuracy of the microphone's test of the photoacoustic signal in the photoacoustic cell 102; the embodiment of the present application sets a first microphone 1021 and a second microphone 1022 to simultaneously test the sound signals at different positions in the photoacoustic cell 102, and subtracts the test results of the two, so as to accurately obtain the photoacoustic signal in the photoacoustic cell 102, which is beneficial to improving the sensitivity and accuracy of characteristic gas detection.

[0067] It should be further explained that, by adjusting the positions of the first microphone 1021 and the second microphone 1022 corresponding to the photoacoustic pool 102, the first microphone 1021 detects the area where the photoacoustic signal is most intense, and the second microphone 1022 detects the area where the photoacoustic signal is weakest; at this time, the sound signal detected by the first microphone 1021 includes two parts: one part is the photoacoustic signal normally occurring in the photoacoustic pool 102, and the other part is the signal generated by the external noise transmitted into the photoacoustic pool 102; the photoacoustic signal detected by the second microphone 1022 is extremely small and can be ignored, so the sound signal detected by the second microphone 1022 only includes the signal generated by the external noise transmitted into the photoacoustic pool 102; by subtracting the sound signal detected by the second microphone 1022 from the sound signal detected by the first microphone 1021, the photoacoustic signal normally occurring in the photoacoustic pool 102 can be obtained, and this photoacoustic signal is the key to determining the concentration of the characteristic gas in the gas sample to be measured.

[0068] Furthermore, the photoacoustic cell 102 further includes a housing 1024 , and the housing 1024 includes a first buffer cavity 102 a , a second buffer cavity 102 b , and a resonant cavity 102 c connecting the first buffer cavity 102 a and the second buffer cavity 102 b . It should be noted that the capacity of the first buffer cavity 102a and the capacity of the second buffer cavity 102b are much larger than the capacity of the resonant cavity 102c, and the resonant cavity 102c is connected between the first buffer cavity 102a and the second buffer cavity 102b in a pipe-like shape. The filling degree of the gas to be detected in the resonant cavity 102c is the highest. Therefore, the resonant cavity 102c is the area where the energy transfer effect between the narrow-bandwidth laser and the characteristic gas is the most intense, and it is also the area where the photoacoustic signal is generated the strongest. Due to its pipe-like structure, the photoacoustic signal generated therein is more easily captured by a microphone. The filling degree of the gas to be detected in the first buffer cavity 102a and the second buffer cavity 102c is relatively low, and the photoacoustic signal generated therein is relatively weak. Moreover, due to their large capacity, it is difficult for a microphone to capture the photoacoustic signal generated therein.

[0069] Furthermore, the first microphone 1021 is disposed on the shell 1024 and corresponds to the middle of the resonance cavity 102c, and the resonance cavity 102c is connected to the first microphone 1021 through an opening on the shell 1024; the second microphone 1022 is also disposed on the shell 1024 and corresponds to the middle of the second buffer cavity 102b, and the second buffer cavity 102b is connected to the second microphone 1022 through an opening on the shell 1024. It should be noted that the first microphone 1021 is set in the middle of the resonance cavity 102c, and can detect a strong photoacoustic signal; the second microphone 1022 is set in the middle of the second buffer cavity 102b, and can hardly detect a photoacoustic signal; in addition, the noise effect generated by the external environmental noise in the first buffer cavity 102a, the second buffer cavity 102b and the resonance cavity 102c is the same, therefore, the sound signals detected by the first microphone 1021 and the second microphone 1022 both contain the external environmental noise of the same intensity, and the photoacoustic signal generated in the photoacoustic cell 102 can be obtained by subtracting the sound signal detected by the second microphone 1022 from the sound signal detected by the first microphone 1021, and then the concentration of the characteristic gas in the gas sample to be measured can be determined by the photoacoustic signal.

[0070] Furthermore, the shell 1024 is also provided with a first air hole 102d and a second air hole 102e. The first air hole 102d is connected to the first buffer cavity 102a, and the second air hole 102e is connected to the second buffer cavity 102b. The first air hole 102d and the second air hole 102e are channels for the gas sample to be measured to flow into and out of the internal cavity of the photoacoustic cell 102.

[0071] Further, the pore unit composed of the first pore 102d and the second pore 102e and the microphone unit composed of the first microphone 1021 and the second microphone 1022 are respectively located on opposite sides of the housing 1024. For example, the first microphone 1021 and the second microphone 1022 are located together at the top of the housing 1024, and the first pore 102d and the second pore 102e are located together at the bottom of the housing 1024, or vice versa. The above design can minimize the influence of the noise generated when the gas sample to be measured flows into or out of the photoacoustic cell 102 on the detection results of the first microphone 1021 and the second microphone 1022, which is conducive to improving the detection accuracy and sensitivity of the characteristic gas concentration.

[0072] Further, the first air hole 102d is the air inlet through which the gas sample to be measured flows into the photoacoustic cell 102, and the second air hole 102e is the air outlet through which the gas sample to be measured flows out of the photoacoustic cell 102; or, the second air hole 102e is the air inlet through which the gas sample to be measured flows into the photoacoustic cell 102, and the first air hole 102d is the air outlet through which the gas sample to be measured flows out of the photoacoustic cell 102. It should be noted that when the second air hole 102e is the air inlet and the first air hole 102d is the air outlet, the flow direction of the gas sample to be measured in the resonance cavity 102c is opposite to the irradiation direction of the narrow-bandwidth laser, which is more conducive to the energy transfer between the characteristic gas in the gas sample to be measured and the narrow-bandwidth laser, and the generated photoacoustic signal is more obvious, which is conducive to further improving the detection accuracy of the characteristic gas concentration.

[0073] Furthermore, a light inlet 1025 and a light outlet 1026 are also provided on the housing 1024. The light inlet 1025 is located on a side of the first buffer cavity 102a away from the resonant cavity 102c, and the light outlet 1026 is located on a side of the second buffer cavity 102b away from the resonant cavity 102c, and the center of the light inlet 1025, the center of the light outlet 1026 and the center axis of the resonant cavity 102c are located on the same straight line. It should be noted that the light inlet 1025 and the light outlet 1026 are channels for the narrow-bandwidth laser to enter and exit the photoacoustic cell 102, and the narrow-bandwidth laser is irradiated into the photoacoustic cell along a straight line from the center of the light inlet 1025, and is emitted along the central straight line of the light outlet 1026 after passing through the first buffer cavity 102a, the resonant cavity 102c and the second buffer cavity 102b in sequence. The center of the light entrance hole 1025, the center of the light exit hole 1026 and the central axis of the resonant cavity 102c are kept in the same straight line, which can ensure that the narrow bandwidth laser is accurately shot into the resonant cavity 102c along a straight line and fully transfers energy with the characteristic gas in the resonant cavity 102c, thereby ensuring the accuracy of characteristic gas detection.

[0074] Optionally, a modulation glass is provided on the light entrance hole 1025, and the modulation glass is used to adjust the parallelism of the narrow-bandwidth laser to ensure that the narrow-bandwidth laser can accurately pass through the resonant cavity 102c.

[0075] Furthermore, the first microphone 1021 includes a first acoustic-to-electric conversion module, which is used to convert the sound signal in the middle of the resonance cavity 102c into a first electrical signal, and input the first electrical signal into the differential operator 1023; the second microphone 1022 includes a second acoustic-to-electric conversion module, which is used to convert the sound signal in the middle of the second buffer cavity 102b into a second electrical signal, and input the second electrical signal into the differential operator 1023.

[0076] Optionally, the first acoustic-to-electric conversion module and the second acoustic-to-electric conversion module have the same circuit structure. Figure 8 , Figure 8 It is a circuit schematic diagram of the first acoustic-to-electric conversion module and the second acoustic-to-electric conversion module provided in the embodiment of the present application. It should be noted that the first electrical signal converted by the first acoustic-to-electric conversion module and the second electrical signal converted by the second acoustic-to-electric conversion module are both analog signals.

[0077] See also Figures 7 to 9 , Fig. 9 : is a circuit schematic diagram of a subtractor provided in an embodiment of the present application. Further, the differential operator 1023 includes a subtractor 40; the in-phase input terminal I1 of the subtractor 40 is electrically connected to the output terminal of the first sound-to-electric conversion module, for receiving the first electrical signal; the inverting input terminal I2 of the subtractor 40 is electrically connected to the output terminal of the second sound-to-electric conversion module, for receiving the second electrical signal; the subtractor 40 is used to obtain a third electrical signal by subtracting the first electrical signal from the second electrical signal, and output the third electrical signal through the output terminal O of the subtractor 40.

[0078] Specifically, the in-phase input terminal I1 of the subtractor 40 is electrically connected to the output terminal of the first sound-to-electric conversion module through the in-phase upper voltage-dividing resistor R1, and the in-phase lower voltage-dividing resistor R2 is electrically connected between the in-phase upper voltage-dividing resistor R1 and the ground point; the in-phase input terminal I2 of the subtractor 40 is electrically connected to the output terminal of the second sound-to-electric conversion module through the reverse resistor R3, and the feedback resistor R4 is electrically connected between the reverse input terminal I2 and the output terminal O; the power supply terminal of the subtractor 40 is electrically connected to the constant voltage source Vcc.

[0079] It should be noted that, since the third electrical signal is the difference between the first electrical signal and the second electrical signal, the third electrical signal has eliminated the interference of environmental noise signals, and therefore, the third electrical signal is equal to the photoacoustic signal in the photoacoustic cell 102 .

[0080] For further information, see Figure 4 and Fig.10 As shown, Fig.10It is a structural schematic diagram of the signal processor provided in an embodiment of the present application. The measuring unit 124 also includes a signal processor 103, and the signal processor 103 is used to receive the third electrical signal output by the differential operator 1023, and perform operations such as amplification, filtering and analog-to-digital conversion on the third electrical signal. Specifically, the signal processor 103 includes a first signal amplifying circuit 1031, a bandpass filtering circuit 1032, a second signal amplifying circuit 1033 and an A / D conversion circuit 1034; the first signal amplifying circuit 1031 is electrically connected to the output end of the differential operator 1023, and is used to perform a first amplification process on the third electrical signal, see for details. Fig.11 The bandpass filter circuit 1032 is electrically connected to the output end of the first amplifier circuit 1031, and is used to filter out the high-frequency and low-frequency signals in the third electrical signal to obtain the intermediate frequency signal in the third electrical signal. Fig.12 The second signal amplifying circuit 1033 is electrically connected to the output end of the bandpass filtering circuit 1032, and is used to perform a second amplification process on the third electrical signal, see Fig.13 The A / D conversion circuit 1034 is electrically connected to the output terminal of the second amplifier circuit 1033 and is used to convert the third electrical signal into a digital signal. Fig.14 .

[0081] The embodiment of the present application eliminates the influence of environmental noise on the photoacoustic signal detection results by setting a first microphone, a second microphone and a differential operator in the photoacoustic cell, thereby improving the accuracy and sensitivity of the measuring unit in detecting the characteristic gas concentration in the gas sample to be tested, which is conducive to timely and accurate determination of operating faults of the oil-immersed equipment.

[0082] See also Figure 4 The measuring unit 124 further includes a laser 101 for generating the narrow-bandwidth laser. It should be understood that the temperature of the laser 101 has an important influence on the stability of the narrow-bandwidth laser generated by the laser 101. Therefore, it is necessary to control the laser 101 to work within a preset temperature range. The embodiment of the present application also provides a temperature control circuit for the laser 101.

[0083] See also Fig.15 and Fig.16 , Fig.15 is a schematic diagram of the structure of a laser temperature control module provided in an embodiment of the present application, Fig.162 is a schematic diagram of a temperature control circuit in a temperature control module provided in an embodiment of the present application. The temperature of the laser 101 is controlled by the temperature control module, which includes a voltage acquisition module U, a voltage controller 201, a voltage stabilizer 202, a voltage comparator 203, a microprogram controller 204 and a thermostat 205, wherein the voltage acquisition module U is used to obtain the effective working voltage of the laser 101, and the voltage controller 201, the voltage stabilizer 202, the voltage comparator 203 and the microprogram controller 204 constitute a temperature control circuit TC of the temperature control module. The voltage controller 201 is used to provide a reference voltage, which is the optimal value of the effective working voltage of the laser 101. That is, when the effective working voltage of the laser 101 is equal to the reference voltage, the laser 101 can emit a narrow-bandwidth laser of a specific frequency and power, and is used to detect the concentration of the characteristic gas in the gas sample to be measured, so that the measurement accuracy and sensitivity of the measurement unit 124 are both optimal; in addition, the closer the effective working voltage of the laser 101 is to the reference voltage, the higher the accuracy and sensitivity of the measurement unit 124 for measuring the concentration of the characteristic gas. The input end of the voltage regulator 202 is electrically connected to the output end of the voltage controller 201, and is used to stabilize the reference voltage provided by the voltage controller 201, eliminate the fluctuation of the reference voltage, and improve the stability and consistency of the reference voltage. The first input end of the voltage comparator 203 is electrically connected to the output end of the voltage regulator 202, and the second input end of the voltage comparator 203 is electrically connected to the output end of the voltage acquisition module U. The voltage comparator 203 is used to compare the effective working voltage of the laser 101 with the voltage value of the reference voltage provided by the voltage controller 201, and transmit the comparison result to the microprogram controller 204. The input end of the microprogram controller 204 is electrically connected to the output end of the voltage comparator 203, and is used to receive and analyze the comparison result, and send a corresponding temperature adjustment instruction to the thermostat 205 according to the comparison result; specifically, when the comparison result is that the effective working voltage of the laser 101 is less than the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to reduce the temperature of the laser 101; when the comparison result is that the effective working voltage of the laser 101 is greater than the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to increase the temperature of the laser 101; when the comparison result is that the effective working voltage of the laser 101 is equal to the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to maintain the temperature of the laser 101. The input end of the thermostat 205 is electrically connected to the output end of the microprogram controller 204 , and is used to adjust the temperature of the laser 101 under the control of the temperature adjustment instruction, so that the laser 101 works within a preset temperature range.

[0084] Please continue reading Figure 1 After the measuring unit 124 uses the narrow bandwidth laser corresponding to the characteristic gas to measure the concentration of the characteristic gas in the gas sample to be measured, the control unit 125 determines the operating failure of the oil-immersed device 11 according to the concentration of the characteristic gas in the gas sample to be measured. When predicting the operation failure of the oil-immersed equipment 11, considering that the fault types of the oil-immersed equipment 11 are different and the corresponding types of characteristic gases are different, the operation failure type of the oil-immersed equipment can be preliminarily judged in advance, and the fault type is predicted by analyzing the type of characteristic gas that appears. After predicting the fault type, it is determined whether the characteristic gas corresponding to the fault type is formed, and after the characteristic gas corresponding to the fault type is formed, the fault type is determined; the specific steps include: determining the type of the characteristic gas according to the concentration of the characteristic gas; presetting the standard concentration change curve corresponding to each fault type, predicting the operation failure type of the oil-immersed equipment according to the standard concentration change curve and the type of the characteristic gas, and obtaining a prediction result; predicting the occurrence of other characteristic gases corresponding to the preset fault type according to the prediction result and the concentration change curve of the characteristic gas; when the other characteristic gases corresponding to the preset fault type appear, determining the operation failure type of the oil-immersed equipment; specifically, the standard concentration change curve corresponding to each fault type is preset to contain the curve of each characteristic gas, and the type of characteristic gas corresponding to each fault type is sorted into a table, as shown in Table 1 below:

[0085]

[0086]

[0087] Table 1

[0088] It can be seen from Table 1 that when the fault type of the oil-immersed equipment 11 is different, the types of characteristic gases measured from the gas sample to be tested are different. For example, when the fault type is cooling oil overheating, the corresponding characteristic gas types are hydrogen, ethylene, methane and ethane; when the fault type is cooling oil and paper overheating, the corresponding characteristic gas types are hydrogen, carbon monoxide, carbon dioxide, ethylene, methane, and ethane; when the fault type is cooling oil and partial discharge in paper insulation, the corresponding characteristic gas types are hydrogen, carbon monoxide, carbon dioxide, acetylene, and methane. , methane, ethane; when the fault type is spark discharge in the cooling oil, the corresponding characteristic gases are hydrogen and acetylene; when the fault type is arc discharge in the cooling oil, the corresponding characteristic gases are hydrogen, acetylene, ethylene, methane and ethane; when the fault type is arc discharge in the cooling oil and paper, the corresponding characteristic gases are hydrogen, carbon monoxide, carbon dioxide, acetylene, ethylene, methane and ethane; when the fault type is damp paper or bubbles in the cooling oil, the corresponding characteristic gas is hydrogen; "-" in Table 1 indicates that the concentration of the characteristic gas in this fault type is 0.

[0089] Based on Table 1, when hydrogen, carbon monoxide, carbon dioxide, ethylene, methane, and ethane are detected, it can be judged that the operating fault type of the oil-immersed equipment may be overheating of the cooling oil and paper or arc discharge in the cooling oil and paper. According to the prediction, and based on the concentration change curve of the characteristic gas, the formation of acetylene, a characteristic gas corresponding to the preset fault type, is predicted. When acetylene is formed, the operating fault type of the oil-immersed equipment is determined to be arc discharge in the cooling oil and paper. When acetylene is not formed, the operating fault type of the oil-immersed equipment is determined to be overheating of the cooling oil and paper, thereby determining the operating fault type of the oil-immersed equipment.

[0090] It should be noted that the characteristic gas can be any one of methane, ethane, ethylene, acetylene, carbon monoxide, carbon dioxide and hydrogen. When measuring the gas sample to be tested, it is necessary to measure the concentration of all types of characteristic gases in the gas sample to be tested; the standard gas sample includes methane, ethane, ethylene, acetylene, carbon monoxide, carbon dioxide and hydrogen, and the sample standard concentration of the characteristic gas in the standard gas sample is a known concentration.

[0091] The fault monitoring device with anti-noise function provided in the embodiment of the present application can realize real-time and online monitoring of characteristic gases in oil-immersed equipment. Compared with the existing method of manual sampling and sending to the laboratory for characteristic gas detection, it greatly improves the timeliness and accuracy of equipment fault warning, and saves time and labor costs. In some special periods, such as during major epidemics, there are fewer workers on duty. The detection of characteristic gases through the existing manual sampling method is not only time-effective, but also difficult to complete the test due to the small number of staff, and the accuracy of the test cannot be guaranteed. At this time, the use of the fault monitoring device with anti-noise function provided in the embodiment of the present application for characteristic gas monitoring further reflects its advantages of low time and labor costs, and timely and accurate detection.

[0092] In summary, the fault monitoring device with anti-noise function provided in the embodiment of the present application includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit connected to the oil-immersed equipment. Through the joint action of each unit module, real-time and online monitoring of the characteristic gas generated in the oil-immersed equipment is realized, so as to timely and accurately determine the operating fault type of the oil-immersed equipment; in addition, by arranging a first microphone, a second microphone and a differential operator in the photoacoustic pool of the measuring unit, the first microphone measures the photoacoustic signal and environmental noise in the photoacoustic pool, and the second microphone only measures the environmental noise in the photoacoustic pool. The measurement result of the first microphone and the measurement result of the second microphone are subtracted by the differential operator to obtain the photoacoustic signal in the photoacoustic pool, thereby eliminating the influence of environmental noise on the photoacoustic signal detection result, improving the accuracy and sensitivity of the measuring unit in detecting the characteristic gas concentration in the gas sample to be measured, and is conducive to further improving the accuracy and timeliness of the fault monitoring device with anti-noise function in determining the operating fault type of the oil-immersed equipment.

[0093] It should be noted that although the present application is disclosed as above with specific embodiments, the above embodiments are not intended to limit the present application. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A fault monitoring device with anti-noise function, characterized in that: Applied to the online monitoring of the operation failure of oil-immersed equipment, the fault monitoring device with anti-noise function comprises an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; wherein: The oil circuit unit is used to obtain a cooling oil sample from the oil-immersed device and input the cooling oil sample into the degassing unit under the control of a sampling enable signal sent to the oil circuit unit by the control unit; The degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested, and input the gas sample to be tested into the gas circuit unit under the control of the degassing enable signal sent thereto by the control unit; The gas circuit unit is used to input the gas sample to be measured into the measurement unit under the control of the measurement enable signal sent to it by the control unit; The measuring unit comprises a laser and a photoacoustic cell, wherein the laser is used to generate a narrow-bandwidth laser of a specific frequency, the photoacoustic cell comprises a first microphone, a second microphone, and a differential operator connected to an output end of the first microphone and an output end of the second microphone, the differential operator is used to obtain a photoacoustic signal in the photoacoustic cell by subtracting an output signal of the first microphone from an output signal of the second microphone, and the measuring unit is used to determine the concentration of the characteristic gas in the gas sample to be measured by the photoacoustic signal generated when the narrow-bandwidth laser corresponding to the characteristic gas irradiates the gas sample to be measured; The control unit is also used to determine the operation failure of the oil-immersed device according to the characteristic gas concentration in the gas sample to be tested.

2. The fault monitoring device with anti-noise function according to claim 1, characterized in that: The photoacoustic cell further comprises a shell, wherein the shell comprises a first buffer cavity, a second buffer cavity, and a resonant cavity connecting the first buffer cavity and the second buffer cavity; The first microphone is arranged on the housing and corresponds to the middle part of the resonant cavity, and the resonant cavity is connected to the first microphone through an opening on the housing; The second microphone is disposed on the housing and corresponds to the middle portion of the second buffer cavity. The second buffer cavity is connected to the second microphone through an opening on the housing.

3. The fault monitoring device with anti-noise function according to claim 2, characterized in that: The first microphone includes a first acoustic-to-electric conversion module, which is used to convert the sound signal in the middle of the resonant cavity into a first electrical signal and input the first electrical signal into the differential operator.

4. The fault monitoring device with anti-noise function according to claim 3, characterized in that: The second microphone includes a second acoustic-to-electric conversion module, which is used to convert the sound signal in the middle of the second buffer cavity into a second electrical signal and input the second electrical signal into the differential operator.

5. The fault monitoring device with anti-noise function according to claim 4, characterized in that: The differential operator includes a subtraction operator; The non-inverting input terminal of the subtractor is electrically connected to the output terminal of the first acoustic-to-electric conversion module, and is used to receive the first electrical signal; The inverting input terminal of the subtractor is electrically connected to the output terminal of the second sound-to-electricity conversion module, and is used to receive the second electrical signal; The subtractor is used for performing a subtraction operation on the first electrical signal and the second electrical signal to obtain a third electrical signal, and outputting the third electrical signal through an output terminal of the subtractor.

6. The fault monitoring device with anti-noise function according to claim 5, characterized in that: The measuring unit also includes a first signal amplifying circuit, a bandpass filtering circuit, a second signal amplifying circuit and an A / D conversion circuit; The first signal amplifying circuit is electrically connected to the output end of the subtractor, and is used to perform a first amplification process on the third electrical signal; The bandpass filter circuit is electrically connected to the output end of the first signal amplifying circuit, and is used to filter out high-frequency and low-frequency signals in the third electrical signal to obtain an intermediate-frequency signal in the third electrical signal; The second signal amplifying circuit is electrically connected to the output end of the bandpass filtering circuit, and is used to perform a second amplification process on the third electrical signal; The A / D conversion circuit is electrically connected to the output end of the second signal amplification circuit, and is used to convert the third electrical signal into a digital signal.

7. The fault monitoring device with anti-noise function according to claim 2, characterized in that: The shell is also provided with a first air hole and a second air hole, the first air hole is connected to the first buffer cavity, the second air hole is connected to the second buffer cavity, and the air hole unit composed of the first air hole and the second air hole and the microphone unit composed of the first microphone and the second microphone are respectively located on opposite sides of the shell.

8. The fault monitoring device with anti-noise function according to claim 7, characterized in that: The first air hole is an air inlet of the gas sample to be tested, and the second air hole is an air outlet of the gas sample to be tested; Alternatively, the second air hole is an air inlet of the gas sample to be measured, and the first air hole is an air outlet of the gas sample to be measured.

9. The fault monitoring device with anti-noise function according to claim 2, characterized in that: The shell is also provided with a light entrance hole and a light exit hole. The light entrance hole is located on a side of the first buffer cavity away from the resonant cavity, and the light exit hole is located on a side of the second buffer cavity away from the resonant cavity. The center of the light entrance hole, the center of the light exit hole and the center axis of the resonant cavity are located on the same straight line.

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